applied science - unit 19 part 4 - chemistry - distinction level - Propose a structure for an unknown compound

Section 4: Propose a structure for an unknown compound using combined spectral analysis

Compound R

Percentage elemental composition:

Carbon: 54.5% Hydrogen: 9.1% Oxygen: 36.4%



IR Spectra




1H NMR




13C NMR

,Mass Spectrum




Empirical Formula:



Percentage Elemental Composition:

, Carbon: 54.5% Hydrogen: 9.1% Oxygen: 36.4%

Empirical Formula calculation:

Step1

53.5% = 53.5g

9.1% = 9.1g

36.4% = 36.4g

Step 2

53.5g/ 12= 4.5

9.1g/ 1 = 9.1

36.4g/ 16 = 2.3

Step 3

4.5/2.3 = 2

9.1/2.3 = 4

2.3/2.3 = 1

Emperical Formula: C2H4O

Molecular Formula:

Mr of Emperical Formula: (2X12)+16+4 = 44

Mass Spectrum:88

Molecular Formula: 88/44 = 2

C2H4O x 2 = C4H8O2




IR Identififcation:

Wavelength: Functional Group:

2900 C-H

1750 C=O

1000+1200 C-O




Possible functional group: